Respirator

ABSTRACT

A breathing apparatus ( 1 ), including a mask ( 2 ) and a neck component ( 3 ). The mask ( 2 ) is adapted to substantially surround at least the mouth or nostrils of a user. The neck component ( 3 ) is attached to said mask ( 2 ), and adapted to substantially surround the back of the neck of said user. The neck component ( 3 ) includes a flow generator to receive unfiltered air from a surrounding environment, filter said unfiltered air, and, provide filtered air to said mask ( 2 ). The breathing apparatus ( 1 ) has a ‘low profile’ appearance and is adapted to sit comfortably about the neck of the user.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of co-pending U.S. patent applicationSer. No. 13/384,577, filed Jan. 17, 2012, which is a National PhaseApplication of International Application No. PCT/AU2010/000902, filedJul. 15, 2010, which claims priority to Australian Patent ApplicationNo. 2009903362, filed Jul. 17, 2009, which applications are incorporatedherein fully by this reference.

BACKGROUND OF THE INVENTION

The present invention relates to a breathing apparatus, and inparticular to a low profile powered air purifying respirator. Thepresent invention also relates to a respirator mask, and a respiratorsystem which has a low profile design, which is comfortable and easy towear about the neck of a user, which is aesthetically pleasing due toits compact construction and low profile appearance, and, which iseffective and efficient to operate in a variety of applications,including everyday applications, on worksites and industrial situations.

DESCRIPTION OF THE PRIOR ART

The reference in this specification to any prior publication (orinformation derived from it), or to any matter which is known, is not,and should not be taken as, an acknowledgement or admission or any formof suggestion that that prior publication (or information derived fromit) or known matter forms part of the common general knowledge in thefield of endeavour to which this specification relates.

A powered air purifying respirator, or PAPR, typically uses power todraw ambient air from the atmosphere through a filter element, topressurize it, and transfer it to the airways of the user via a conduitand mask. A PAPR ensures that the supply of air remains filtered orpurified under all circumstances by maintaining a positive pressureinside the mask. PAPR devices are currently used where the environmentis heavily polluted or hazardous, to supply purified air to a user. Suchenvironments traditionally include polluted industrial areas, orhospitals.

All currently known PAPR systems are specified solely for professionaland industrial applications. That is, they have not been designed foruse by the general public in everyday situations. Therefore, the size ofmost PAPR systems is typically big and heavy.

Some known PAPR systems have filtering capability relocated to thehardhat/or helmet (4,462,399), but this attempt does not improvecompactness, nor encourage a lightweight structure, but rather, makesthe device bulky and top-heavy for users' heads. Some known PAPR systemscan be carried as a backpack, encased in elastic bag with shoulderstraps to carry the device, however, this is as portable as the devicecould be, and does not allow for other carrying methods when thestrap/bag configuration is not used. As a result, most existing PAPRsystems would not encourage users to use these systems other than whenit is really necessary, that is, in toxic or hazardous areas which occurin industrial environments.

For the general public, protection from pollution and disease in theirdaily life relies largely on dust or surgical marks. However, thesemasks only provide basic protection, due to leakage around the masks,even when the filter material used in making such masks is typicallylabelled as suitable for high efficiency filtering. Due to the extraresistance imposed by the filter media, the user has to breatheconsiderably harder than they normally do without the mask. Thus, it isquite difficult for anyone to use such a mask comfortably for aprolonged period. Furthermore, CO2 and moisture accumulate inside themask, which tends to make the situation worse. In addition, the higherthe efficiency of the filter media, the higher the flow resistance itwill impose, thus making these masks even more uncomfortable forprolonged use. Such effects are particularly obvious for those who haveweak or impaired respiratory systems, such as elderly people, children,and the sick, such as asthma and COPD patients.

Dust and surgical masks have therefore been widely used by generalpublic largely because of their ease of use and the fact that there arenot any acceptable PAPR solutions available should anyone wish to use amore efficient and comfortable device. However, it is apparent that theair quality in many everyday situations can be very poor. In largercities, the heavy density of cars, buses, trucks and motorcycles oftenemit excessive amounts of toxic pollutants. Power plants are another keysource of pollutions.

Natural or man-made disasters, such as sandstorms, fires of any kinds,also contribute harm to people's respiratory systems. Those pollutionsinclude dust (suspended particles), lead, and harmful gases such as NO2,SO2. CO, 03, VOCs, smoke, etc. Long term exposure to these pollutions isevidenced to be harmful and often causes life threatening diseases.SARS, bird and swine influenza, three of the most recent disease-relatedthreats to humans are also pollutants, or air borne diseases, and arepotentially deadly to human beings.

A protection device that offers the similar level of protection andcomfort to PAPR and yet can also be acceptable to use by ordinary peopleor light industrial/professional users is clearly needed.

SUMMARY OF THE INVENTION

The present invention seeks to overcome the deficiencies of the priorart. The present invention also seeks to provide a low-profilerespirator.

Throughout this specification, the term ‘low profile’ is used. This termis intended to refer to a mask which, whilst covering the nose and/ormouth of the user similar to that of a ‘dust mask’, is relatively smalland compact in size and shape, such that it is relatively aestheticallypleasing in appearance when worn, particularly compared with thetraditional bulky and heavy industrial masks of known poweredrespirators. Such prior art powered respirators used in industrialapplications appear cumbersome and typically have air tubes supplyingthe air into the mask chamber provided on the front of the masks,rendering those masks particularly aesthetically unappealing.

The present invention also seeks to provide a respirator which includesone or more of the advantages of being easy to carry, easy to don anddoff, having improved perception/image while in use, and, which is costeffective.

The present invention also seeks to provide a low profile respiratorwhich can function as a pollution protection device, or as a breathingassistance or breathing therapy apparatus. Typical examples of people indomestic environments who may benefit from such a said device includedaily commuters; motorcyclists, electric bicycle riders, passengers,pedestrians and road workers, traffic officers, road repairers,construction workers, airport staffs, clean room/laboratory workers,food processing workers, poultry farmers, those working in hospitalstreating and containing outbreaks, schools, smoke zone workers, etc.

In one broad form, the present invention provides a breathing apparatus,including:

a mask, adapted to substantially surround at least the mouth or nostrilsof a user; and

a neck component, attached to said mask, adapted to substantiallysurround the back of the neck of said user, said neck componentincluding a flow generator to receive unfiltered air from a surroundingenvironment, filter said unfiltered air, and, provide filtered air tosaid mask;

an inlet air channel arranged to convey air from the flow generator tothe mask; and

an outlet air channel, separate from the inlet channel, arranged toconvey air from the mask, wherein the inlet air channel and outlet airchannel open to the mask at opposite sides of the mask, so that the airflow is arranged to flow across the mouth or nostrils of the user.

Preferably, said neck component is attached to said mask by at least oneengagement arrangement.

Preferably, each said engagement arrangement includes: at least onecooperating air channel on said mask and said neck component; at leastone cooperating mating clip to releasably mate said mask and said neckcomponent together. Also preferably, each air channel is at least partlyformed of an elastomeric material.

Also preferably each mating clip includes a ratchet. Preferably at leasta seal portion of said mask is at least partly formed of silicone rubberor the like.

Preferably said filtered air is transferred between said neck componentand said mask via integrally formed air channels. Also preferably, allcomponentry for operation of said breathing apparatus are housed withinsaid neck component.

Preferably, said neck component further includes any one or combinationof:

a flow sensor;

a pressure sensor;

a negative ion generator;

a heater;

a cooler,

a filter assembly;

a blower,

a power supply;

a muffler;

a user interface; and

a humidifier/dehumidifier.

Preferably the present invention further includes a cover, to decoratesaid mask, including fabric or other material, and/or a visor to provideprotection to the eyes of said user. Also preferably the presentinvention further includes a strap or band, adapted to be attached overthe head of a user, to retain said mask in position.

Preferably said flow sensor and/or said pressure sensor is adapted toprovide a feedback signal to said flow generator to adjust said air flowand/or air pressure of said mask, that is, be breath responsive, saidbreath responsiveness of said flow/pressure sensor being optionally useradjustable.

Also preferably, said filter assembly further includes any one orcombination of:

a coarse filter,

a pre-filter,

a high efficiency particulate air (HEPA) filter,

an advanced carbon filter;

an activated carbon filter (steam activated or multiple chemicalactivated);

a photo catalyst filter or coating (ambient light and/or LED activated);and

a cold catalyst filter.

Preferably said neck component further includes control means, saidcontrol means including any one or combination of:

a user controlled interface;

a remote controller,

a rechargeable battery;

a battery pack; and

a motor controller.

Also preferably said apparatus is manufactured to have a ‘low profile’appearance, and which is adapted to sit comfortably about the neck ofsaid user, optionally including padded portions.

Preferably, said breathing apparatus includes: a sensor, to sense thetemperature and/or humidity of said air; a comparator, to compare saidsensed temperature and/or humidity with a predetermined value; and,climate control means including at least one of a heater, cooler,humidifier and dehumidifier, to provide any necessary adjustment oftemperature and/or humidity of said filtered air provided to said maskto said predetermined value. Also preferably, said predetermined valueis either preset by a manufacturer or is user adjustable.

Preferably, said breathing apparatus includes a negative ion generatorhaving a control to operate in sync with a users' breathing pattern (onwith inhalation and off with exhalation).

Preferably, said breathing apparatus includes a brushless DC motorhaving a stator with a toroidal core, characterised in that said coreincludes a plurality of radial fins extending inwardly therefrom to forma divide between respective coils formed therebetween.

Also preferably, said radial fins are formed either by integrallymoulding with the core, or, by overmoulding the core.

Preferably, said breathing apparatus further includes an exhaled airfilter, to filter air exhaled by said user before being egressed to thesurrounding environment.

Also preferably, said exhaled air filter is integrally formed with anexhaust valve of said breathing apparatus. In a further broad form, thepresent invention provides a mask, adapted to substantially surround atleast the mouth or nostrils of a user; and, a climate control means,including at least one of a heater, cooler, humidifier and dehumidifier,to adjust the temperature and/or humidity of said air provided to saiduser. Preferably, the breathing apparatus further includes a filter toreceive unfiltered air from a surrounding environment and providefiltered air to said mask.

In a further broad form, the present invention provides a mask, adaptedto substantially surround at least the mouth or nostrils of a user; and,a negative ion generator having control to operate in sync with a user'sbreathing pattern (on with inhalation and off with exhalation).

In yet a further broad form, the present invention provides a mask,adapted to substantially surround at least the mouth or nostrils of auser; and an exhaled air filter to filter air exhaled by a user beforebeing egressed to a surrounding environment.

Preferably, said exhaled air filter is integrally formed with an exhaustvalve of said breathing apparatus.

In a further broad form, the present invention provides a brushless DCmotor having a stator with a toroidal core including a plurality ofradial fins extending inwardly from said core to form a divide betweenrespective coils, wherein said radial fins are formed either byintegrally moulding with the core, or by overmoulding the core.

In accordance with further aspect, the present invention provides abreathing apparatus, comprising:

a mask arranged to substantially surround at least the mouth or nostrilsof a user;

a flow generator arranged to receive unfiltered air from a surroundingenvironment, filter the unfiltered air and provide an air flow of thefiltered air to the mask; and

a sensor and a controller arranged to determine a required air flowrate, and to control the flow generator to adjust the air flow to themask according to the required airflow rate, wherein the sensor and thecontroller is arranged to measure a rate of change of air flow atinhalation of the user in order to determine required air flow rate.

In accordance with yet a further aspect, the present invention providesa breathing apparatus, comprising:

a mask arranged to substantially surround at least the mouth or nostrilsof a user;

a flow generator arranged to receive unfiltered air from a surroundingenvironment, filter the unfiltered air and provide an air flow offiltered air to the mask; an inlet air channel arranged to convey airfrom the flow generator to the mask; and

an outlet air channel separate from the inlet air channel, arranged toconvey air from the mask, wherein the inlet air channel and outlet airchannel open to the mask at opposite sides of the mask, so that theairflow is arranged to flow across the mouth or nostrils of the user.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thefollowing detailed description of preferred but non limiting embodimentsthereof, described in connection with the accompanying drawings,wherein:

FIG. 1 shows a person wearing a breathing apparatus in accordance withthe present invention;

FIG. 2 shows a perspective view of the breathing apparatus;

FIG. 3 shows an exploded perspective view of the breathing apparatus ofFIG. 2;

FIGS. 4A and 4B respectively show front and rear perspective views ofthe mask component of the breathing apparatus:

FIG. 5 shows a perspective view of the neck component of the breathingapparatus which incorporates the flow generator;

FIG. 6 shows a sectional view of the breathing apparatus, showing theair paths;

FIG. 7 illustrates the typical component features which may beincorporated in the breathing apparatus of the present invention, andtheir interrelationship;

FIGS. 8A-8C detail the engagement arrangement which may be used toengage the mask and neck component together;

FIG. 9 details a heater which may be installed in the breathingapparatus;

FIG. 10 illustrates the provision of a humidifier which may be installedin the breathing apparatus;

FIG. 11 details an alternative humidifier which may be installed in thebreathing apparatus;

FIG. 12 shows an integrally formed filter and humidifier wick;

FIGS. 13A-13C show another alternative wicking design for the breathingapparatus;

FIGS. 14A-14B illustrate a different design of wicking fingers;

FIG. 15 shows the provision of an alternative heater in the breathingapparatus;

FIG. 16 shows a filter assembly for the breathing apparatus;

FIGS. 17A-17B show a typical filter replacement procedure;

FIGS. 18A-18I show various exemplary configurations of different filterconfigurations;

FIGS. 19A-19E show various exemplary flowcharts of the steps used in theresponsive flow control of the flow generator module of the presentinvention;

FIGS. 20A-20B show embodiments of a responsive flow system in accordancewith the present invention;

FIG. 21A details a core arrangement according to the prior art. FIG. 21Bdetails a toroidal core arrangement for use in the breathing apparatusof the present invention; and

FIGS. 22A-22B show an alternative version of the invention, including avisor.

DETAILED DESCRIPTIONS OF THE PREFERRED EMBODIMENTS

Throughout the drawings, like numerals will be used to identify similarfeatures, except where expressly otherwise indicated.

Respirator Mask Assembly

The respirator or breathing apparatus assembly of the present invention,includes a mask component and a neck component. The mask component isadapted to substantially surround the mouth and/or nostrils of the user,whilst the neck component is attachable thereto and is adapted tosurround the back of the neck of the user. The neck component includesthe flow generator and associated processing means to receive unfilteredair from the surrounding environment, filter the unfiltered air andprovide the filtered air to the mask.

FIG. 1 illustrates a person wearing a breathing apparatus in accordancewith a preferred form of the present invention. As illustrated, theapparatus 1 is of considerably improved aesthetically pleasing visualappearance, and is relatively low profile compared with prior artrespiratory devices. The mask is relatively comfortably worn covering atleast the mouth or nose of the user, and extending around the neck ofuser. All componentry in the breathing apparatus, may be whollycontained within this face and neck assembly.

FIG. 2 illustrates a perspective view of the breathing apparatus 1,including a mask component 2 and a neck component 3, which are at leastpartly detachable from each other.

FIG. 3 illustrates an exploded view of the breathing apparatus 1,showing the mask component 2 separated from the neck component 3. Thisis achieved by an appropriate cooperating engagement means 4 provided onthe mask 2 and neck component 3 to engageably attach the assemblytogether.

FIGS. 4A and 4B illustrate front perspective and rear perspective viewsof the mask component 2, respectively. FIG. 5 illustrates a perspectiveview of the neck component 3 which is attachable to the mask component 2of FIGS. 4A-4B.

Referring to FIGS. 1 to 5, it can be seen that the mask component 2 isadapted to surround the oronasal area, that is, the mouth, nostrils ornose of a user. Alternative embodiments may cover either one of themouth or nose, having an even lower ‘low profile’ appearance.

At least part of the mask component 2 may preferably be formed of asuitable material, to provide a good seal between the face and the airpaths of the mask 2, whereby leakage of air/gas is substantiallyavoided, to effectively provide an airtight seal by sealingly contactingand “cushioning” the face of the user. The mask components may typicallybe made of plastics or rubber materials, such as rubber or silicone. Themask component 2, when formed of such material, may then be washed orsterilised, as required.

A cover may be optionally provided to decorate the mask. The cover maybe formed of fabric or other material. An in-mould decoration may bealternatively or additionally provided to the mask.

As shown in FIG. 6, a breathing chamber 5 is provided in the spacebetween the face of the user and the shell of the mask 2. The breathingchamber 5 is effectively isolated from the surrounding environment byvirtue of a seal about the face of the user. One or more air channels,ducts, or conduits 6 and 7 may be provided to connect the breathingchamber 5 with the other parts of the breathing apparatus. In theembodiment shown in FIG. 6, there is provided, in the mask 2, an airinlet 6 and an air outlet 7, for this purpose.

When the mask 2 is attached to the neck component 3, continuous airchannels are therefore provided between the two components. The meansfor attachment of these two components will be described hereinafter.The neck component 3 of FIG. 5, is adapted to be attached to the mask 2,and in use, is adapted to substantially surround the back of the neck ofthe user. The neck component 3 includes the flow generator means forgenerating the flow of air to and from the mask component 2, takingunfiltered air from the surrounding environment through an air intakemeans 8, filtering the unfiltered air via a filter 9, and effecting aflow of air by a motor or impellor 10, through the air channel 6 to themask chamber 5. Air exhaled into the mask by the user chamber 5 is thenprogressed via air channel 7 through outlet 11 to the surroundingenvironment. The typical flow of air within the breathing apparatus 1 isshown by the arrows in FIG. 6.

Appropriate electronic components 12, a battery 13 or the like and othercomponents are all preferably housed within the neck assembly 3. Theneck assembly also preferably incorporates a neck pad 14 to providecushioning for comfort of the user and is also to help maintain the maskseal as the user's head undergoes movement.

In FIG. 7 is shown a block diagram of various component features whichmay be typically included in the breathing apparatus, showing that mostare installed in the neck assembly 3, and, their interrelationship. Alsoshown is the provision of an optional additional power pack, and theinterrelationship of the neck assembly via the air channel to the maskassembly.

Pneumatic Connection and Tension Transmission Clip

Existing PAPR devices use separate means for securing the mask to theface and for supplying air to the mask. For instance, many PAPR use aflexible hose to supply air from the flow generator to the mask, and, aseparate head strap to hold the mask on the face. Others mount the fanin an enclosure on top of the user's head and discharge the air directlyinto the mask, but use a separate strap or band to hold the mask againstthe face.

In these prior art devices, the user is forced to assemble and releasemultiple connections every time he or she dons or doffs the device.Also, in those devices where the fan is mounted integrally with themask, there is a great risk that washing the mask (which is necessaryfor hygiene) will cause water damage to the fan or control electronics.

Ideally both the air supply to the mask and the tension to keep it inplace would be supplied by a single connection between the flowgenerator and the mask. Ideally also it would be easy to completelydisconnect the mask from the flow generator, for cleaning. The presentinvention achieves both of these objectives with a component thatcombines the functions of a pneumatic connector with those of a clip (asused on a backpack or other piece of luggage).

The engagement arrangement, shown in FIGS. 8A-8C, consists of twocomponents, a mask portion 21 and a neck portion 22, each secured to anelastomeric tube. Each component has a respective air channel 23 and 24,so that air can pass through the clip 20. A seal is formed on one of theelastomeric tubes, so positioned that when the clip is assembled itpresses against the opposite clip half. This seal may take the form of acircular cross-section element (like an o-ring) however it is preferablya wiper seal as this design creates less friction when the clip isassembled or dismantled. Alternatively the seal may be a separatecomponent (for instance an o-ring) that is fitted to or over-moulded onone or other clip half.

The two halves of the engagement arrangement 20 are so designed as toprovide the ability to transmit tension from one elastomeric tube to theother, but to also be easy to release. For instance they may be providedwith one or more beam-like elements with barbs that snap into matingfeatures on the opposite half of the clip. The barbed features take theform of large buttons. Pressing on them disengages the barb(s) andallows the two halves to be separated.

In the preferred embodiment two such engagement arrangements 20 areused, one in the air-supply pipe and one in the air-return pipe. Innormal use only one of the clips is disconnected when removing thedevice from the head. However when mask cleaning is required the otherclip can also be opened, so that the flow generator or neck component isentirely separated from the mask.

Single Action Adjustment of the Mask

Existing designs of PAPR rely on either an elastomeric strap or someform of rigid band to maintain tension on the mask and thus seal itagainst the user's face. Both types of systems can be difficult and slowto adjust and tend to suffer from other problems. In particular, theadjustment mechanisms for such elastomeric straps tend to requireconsiderable force for their adjustment. Rigid systems do not compensatefor any change in the distance between the flow generator and the user'sface for instance during head movement. For this reason they tend tosuffer leaks between the mask cushion and the face.

In FIGS. 8A-8C are shown details of an engagement arrangement which maybe utilised with the breathing apparatus of the present invention, toengage the neck component and the mask together. The engagementarrangement is shown engaged in FIG. 8A and in exploded view in FIG. 8B.A sectional view is also shown in FIG. 8C. The engagement arrangement20, includes a mask portion 21 and a neck portion 22, and includescooperating air channel apparatus 23 and 24, and cooperating matingmeans 25 and 26 to physically clip the components together in areleasable manner. Additional attachment means 27 may be optionallyprovided to engage an additional elastomeric strap which may be placedover the head of a user. A ratchet mechanism 28 may also be provided foradjustment of the ‘size’ of the assembled breathing apparatus, as willbe hereinafter described.

FIG. 8C shows a cross-sectional view of the engaged air channelcomponents 23 and 24, illustrating how an air-tight air channel isthereby formed.

The present design overcomes the deficiencies in prior art devices byproviding a number of unique features. Firstly, the mounting point ispreferably designed to be provided approximately half way between theneck component and the mask. The mounting point preferably takes theform of a clip that allows the neck component to be separated from themask. Secondly, an elastomeric tube is preferably utilised from themounting point to the mask. The elastomeric tube does not then have tobe adjusted in length, but it is able to provide some elasticity in theconnection between the neck component and the mask, to thus compensatefor changes in the flow generator-to-face distance, as the user moveshis or her head. Thirdly a rigid link connection is provided between themounting point and the neck component. Also, a ratchet mechanism may bemounted on the neck component and working between it and the rigid linkto the mounting point. The mechanism is preferably constructed so thatit readily allows the rigid link to be shortened, but will not permit itto be lengthened unless a release button is pressed.

In operation this mechanism may typically work as follows. The breathingapparatus may be initially supplied to the user set to the largest size(i.e. with the rigid link set at its greatest length). When the usertries on the breathing apparatus for the first time, they have only toplace one hand on the neck component (behind their head) and the otheron the front of the mask (in front of their face) and push the twogently together. With this single action it is possible to achieveexactly the desired degree of tension between neck component and mask.

Air Humidity/Temperature Control

In cold and/or dry climates lack of adequate humidity in the air cancause significant discomfort, including drying and cracking of the nasalpassages and lips and a feeling of deep cold in the nose. None of theexisting PAPR designs offers control of either the temperatures or thehumidity of the mask air. The present invention seeks to remedy thesedeficiencies, rendering the breathing apparatus comfortable to wear/usein any climatic conditions. FIGS. 9 to 15 illustrate examples of airtemperature/humidity control devices which may be typically used in thebreathing apparatus of the present invention.

The heater/cooler may be placed anywhere in the air stream, for instanceas shown in FIGS. 9 to 12, the heater/cooler 40 directly behind theinlet filter 41, between the filter and the blower or, as shown in FIG.15, the heater may be placed in the duct between the blower 42 and theduct 48 to the mask, or, in the mask itself.

By way of example, the following types of heating elements may typicallybe incorporated in the breathing apparatus. These include flexibleheating elements (made from copper or nickel-based tracks sandwichedbetween layers of plastic insulator such as polyester or polyimide) andheated by passing an electric current though them, other heatersconsisting of electrically resistive elements, devices using the Peltiereffect (which can heat or cool—for instance the OptoCooler HV 14 devicefrom Nextreme Thermal Solutions), electrically resistive wires withinthe air path or mask or embedded in the walls of those structures,and/or, heaters in which an electrically conductive ink is printed on asubstrate and an electric current passed through it.

Also, by way of example suitable cooling devices may typically includedevices using the Peltier effect (for instance the OptoCooler HV 14device from Nextreme Thermal Solutions), and/or, evaporators, in which aliquid is put in thermal contact with the air stream and allowed toevaporate, wherein the energy required to change the fluid from a liquidto a gas is supplied by the air stream, which is cooled as it passesover the liquid.

In a preferred form the device regulates mask air temperature based onreadings from a temperature sensor at or near the mask.

Alternatively the device may sense ambient air temperature and thencalculate the temperature of the mask air based on its reading (or anestimate) of the air flow rate. In this implementation the device readsthe ambient air temperature and (optionally) the air flow rate. It thenconsults a look-up table of experimentally determined values that tellit how much the air will heat or cool as it passes through the device tothe patient. Alternatively the experimentally determined heating/coolingvalues may be embodied in a mathematical formula that allows theexpected mask air temperature to be calculated.

The target mask air temperature is preferably under the control of theuser (i.e. the user can set the target temperature). Alternatively thetarget air temperature can default to some value that most users findcomfortable. Ideally the default value may be different depending on theambient temperature. For instance most users will find a temperature of30-32 degrees C. comfortable when the weather is cold, but may prefer alower temperature (perhaps 18-20 deg C.) when the weather is hot.

To control mask air humidity the breathing apparatus may be providedwith a water reservoir 43 and a means of producing controlledevaporation. The water tank may be placed inside the flow generator orcan be made to clip onto it, or can be located elsewhere (for instanceon the user's belt) and provided with a tube or other arrangement fortransferring water from it to the evaporator module. It may beconvenient to combine the evaporator module with the heating/coolingmodule.

The evaporator may be placed anywhere in the airstream, for instancedirectly after in the inlet filter, between the blower and the mask orinside the mask. The evaporator may take many forms, as explained below.

One form of evaporator module may be implemented as shown in FIG. 11,having a sheet or roll of a wicking material 44 that automaticallytransfers water from wet to dry areas. Examples include cloth or otherstructures made from cotton or burlap or from man-made fibres such asbare fibre-glass. This form of evaporator will preferably be held inclose contact with a heater 40 to promote rapid evaporation and also toreplace the energy lost when the water changes from liquid to vapour. Inthis way the cooling effect of evaporation may be regulated oreliminated. Preferably this sort of wick 44 is easily replaced. Regularreplacement of the wick is important to avoid the build-up ofcontaminants from the water (e.g. calcium carbonate) and the growth oforganisms on the wick. An example of a wick that is easy to change isshown in FIG. 12. In this example the wicking element 45 has beencombined with the filter element 41, which itself is attached to afilter frame 46 so that it is changed every time the filter is replaced.

An alternative wicking design is shown in FIGS. 13A-13C. The heatertakes the form of four “fingers” 50, positioned in the air path (shownby arrows) just after the inlet filter.

Sleeves of wicking material 52 are fitted over these fingers. Water issupplied to the sleeves 50 from a tank via inlet 51. Heat from thefingers 50 causes the water to evaporate and pass into the air stream.

When the cotton sleeves 52 need to be changed, the structure pivots outinto the filter area as shown in FIG. 13B. Two alternative versions ofthis design are shown in FIGS. 13A-13C and 14A-14B. In the first, asshown in FIGS. 13A-13C, water is supplied from small nozzles 53positioned so as to press against the outside of the wicking sleeves 52.In this implementation the heaters 50 may be metal tubes into whichresistive wires are placed. In the second implementation, as shown inFIGS. 14A-14B, the heating fingers 50 are hollow and are provided withsmall weep holes 54 around their periphery. Water is introduced into thefingers 50 and makes its way via the weep holes 54 into the wickingsleeves 52 and from there into the air path. In FIG. 10, an ofevaporator module is shown which uses membranes, to separate the liquidwater from the air path. These systems consist of a water reservoir 43covered by a material 44 that allows water vapour but not liquid waterto pass.

Examples of this sort of material are expanded PTFE membranes (Gortex byWL Gore and similar) and flashspun high density polyethylene (Tyvek byDupont and the like). The reservoir may be heated or unheated, althoughan unheated reservoir will provide low humidity output. In the heatedversion the water is heated to some high temperature (up to 100 deg C).Vapour passes through the membrane into the air stream. However theliquid water cannot pass through the membrane, even when the reservoiris agitated or inverted. The reservoir can be a small volume supplied bythe main water tank; or it can be the tank itself.

The membrane 44 covering the reservoir 43 is prone to clogging due tocontaminants in the water. It is preferable that this membrane be easilychanged.

As the joint between the membrane and the rest of the reservoir issubject to some pressure differential (due to the heating of the waterand its resistance to vapour flow), the membrane is preferablyfactory-sealed to the reservoir. In the implementation shown, areservoir is provided on the back of the filter element. The reservoirhas one side made from a vapour-permeable membrane as described above,while the other is made from metal foil. Alternatively, the metal foilmay be replaced with a plastic, either in its natural state or coatedwith a metal (for instance aluminium) to improve its heat transfercharacteristics. When the filter is fitted, the metal-foil side of thereservoir is pressed against a heater mounted within the flow generator.The metal-foil half of the reservoir is sealed (glued or welded) to thevapour-permeable membrane, which faces into the air path. Water is fedinto the reservoir from an external tank. Heating the water in thereservoir causes evaporation. The water vapour passes into the airstream, while the liquid remains in the reservoir. Preferably theexternal tank is sited above the reservoir. If this is done thereservoir will be filled automatically by gravity-feed.

Alternatively the membrane may be provided with some easy method ofensuring a tight seal between itself and the reservoir. Examples includeself-adhesive seals and rubber seals. In a design using a self-adhesiveseal the replacement membrane is provided with a piece of double-sidedadhesive material (for instance VHB tape by 3M). One side of the tape isbonded to the membrane in the factory, while the other side is leftcovered by a protective covering. To replace the membrane, the old oneis removed, the protective covering is peeled from the tape seal and thenew membrane is stuck in place. In a design using a rubber seal, acompliant material (for instance a thermo-plastic elastomer such asSantoprene by Exxon Mobil Chemical) is moulded around the edge of themembrane. In use this material is compressed between flange on thereservoir and another component of the flow generator so as to create aseal.

An additional advantage of using a membrane between the water and theair path is that most such membranes can block the movement of bacteria,thus providing a level of protection against the use of contaminatedwater in the humidifier. Ideally mask air relative humidity (RH) iscontrolled by reference to a RH sensor in or near the mask. This sensorwill ideally sense both absolute humidity (grams of water per litre ofair) and temperature, allowing it to calculate the relative humidity.

Alternatively, the device can sense ambient humidity and then use itsknowledge (or estimate) of mask air temperature to infer the relativehumidity in the mask.

The target mask humidity may be under the control of the user, forinstance by having a “Mask RF” setting in the user interface.Alternatively, the device can target a default value that has been foundexperimentally to suit most users. This value is generally in the rangeof 60% to 80% RH.

Alternatively the user can control humidity via an open-loop system inwhich the user controls the power to the evaporator module. In somesituations, for example, due to manufacturing costs or environmentalconditions, a full heating/cooling module with a humidifier is notessential. In a broad range of areas in the northern hemisphere, coldand wet condition may present for quite a long time of a year, such asthe United Kingdom, Russia, and Canada. Instead, a compact heatingmodule 47, as shown in FIG. 15 requiring little space in the device andmanufacturing cost can be favoured in raising mask air temperature. Inthe meantime, an easy-fit-removal heating module can be adjusted to aparticular market by quickly changing assembly process rather than mucheffort to modify the device. This heating module embodiment includesthree major components, a heating element, heat insulation, and support.

A heating element may be used to generate heat to add to passing air.Various types of heaters suitable in this embodiment, including a PTCheater, highly compact coil heater. The power can be supplied from thePCB with an extra plugging wire just like the other energy consumingparts of the device. An embodiment of a heating module is illustrated inFIG. 15, wherein it is shown that the heating module is provided in theair stream of the breathing apparatus.

PTC is known for its high compatibility and outstanding outputperformance. This ceramic block can be manufactured to meet differentstandards with various voltage inputs and output powers.

A thin plate of PTC heater can sit in the air pathway and it is usuallymade into honeycomb to supply relatively large surface area andstructure stability. Air is pumped towards the heated plate and isforced to squeeze through the honeycomb. During this process, heat ispicked up by relatively cooler air. Once air leaves the plate and entersthe bellow, it has been warmed up.

Coils have a long history as heating elements. Their simple structureenables low tech manufacturing and it can be made highly compact withseveral rounds of coils in a limited space. In the meantime, itsperformance has a linear relationship to its structure, and this makesit easy to control.

Similar to the heater in a hair dryer, coils can be added into the airpathway in a module. The large surface area and the least interferenceto the airflow offer smooth heat transfer. It has been shown that coilheaters are capable of heating a large volume of airflow to a desiredtemperature.

Flexible heaters consist of high performance heating wires embraced intwo layers of dielectric isolation material. With thin aluminium finsattached to the both sides of its surfaces, it has a great potential todistribute heat into air uniformly. Due to its flexibility, this type ofheater can be bent into an irregular shape to fit into the air path.

Filter Assembly

Existing PAPRs often need to use specific gas filters for specific gasesand often target the environment with rather high gas concentration thatdemands significant physical size for a given filter. This is notpractical for typical city street pollutant protection, where the gaspollutants can be one or all of CO, NOx, SO2, 03, VOCs, smokes, Ammonia,etc but with relatively lower concentration than in a typical industrialenvironment that most PAPRs target at. This invention describes aspecial filter in a low profile configuration that in addition toparticulate filtration is also capable of filtering most common streetgas pollutants from unhealthy to good inside the mask. The gas filteringis achieved by one of or both of an activated carbon filter and photocatalyst filter. Said photo catalyst filter is preferably made in TiO2,and is reactive in all sorts of light, preferably in standard LEDs. Thismakes UV light unnecessary which helps improve product safety.

The filter assembly, is shown in FIG. 16A in its assembled form, and, inFIG. 16 B in exploded form. The filter assembly 60 includes a filterframe 61, a main filter core 62 (illustrated as a HEPA filter), and aparticulate filter cover 63. Also shown is a boston valve 64. The filteris preferably housed in a low profile enclosure with a user removablefilter cover. The filter cover 63 has multiple openings/slots to let inthe air and also to bring in ambient light. The filter cover 63 as wellas the enclosure body can be also light transparent. A light reflectingcoating can be applied on the inside of said filter cover. Said filtercover is separated with the filter element 62 by a thin gap. The gapprovides a space for an even airflow distribution through the filter 62.It also provides space needed for ambient light to be better distributedon the surface of the filter if applicable.

Most existing respirators use valves to control the exhaust air from themask. The valve closes at inhalation and opens at exhalation. However,this mechanism allows breathed air unfiltered before exiting to theenvironment. In certain situations, this is undesirable or even harmfulto others, such as when a virus infected patient wears the device, orthe device is worn by food processing workers. This invention introducesa valve and filter combination for exhaust air. As shown in FIG. 16B,filter 63 provides filtration to exhaust air in combination with valve64. FIGS. 17A-17B show how the filter may be easily replaced by a user,FIG. 17A showing the assembled unit 70, whilst FIG. 17B showing the unit70 in exploded form, wherein the filter cover 71 is removed forreplacement of the filter 60. To remove the filter, firstly, the filtercover is opened by inserting the user's finger at cutout 72. The filtercover is then able to be moved apart from the unit 70, due to theprovision of an over-centre latch 73, such that the filter can then beremoved as indicated by the arrow in FIG. 17B.

Various optional types of filters may be alternatively used, as shown inFIG. 18A to 18H. In one embodiment, shown in FIG. 18A said filterassembly 80 consists of a pre-filter 81 and a HEPA particulate filter82. Said pre-filter 81 is the first filter element behind the filtercover 83 and protects said HEPA filter 82. Both said pre-filter 81 andHEPA filters 82 are preferably easily removable by users. The pre-filter81 may made from a suitable synthetic fibre such as polypropylene, andpreferably with efficiency equal to or better than 90% for particle sizeof 5 um and above. Said pre-filter 81 is not pleated making it suitableas a base material to be impregnated with photo catalyst media. Inanother embodiment, shown in FIG. 18B, said filter assembly 80 consistsof a pre-filter 81, an activated carbon filter 84 and a HEPA particulatefilter 82. Said pre-filter 81 is the first filter element behind thefilter cover 83 and protects said activated carbon 84 and HEPA filter82. All filters are easily removable by users. In another embodiment,shown in FIG. 18C, said filter assembly 80 consists of a photo catalystmedia plus pre-filter 85, an activated (typically steam activated)carbon filter 84 and a HEPA particulate filter 82. Said pre-filter 85 isthe first filter element behind the filter cover 83 and protects saidactivated carbon 84 and HEPA filter 82. All filters are easily removableby users. Said photo catalyst media 85 is activated when daylight isavailable. Once activated, said photo catalyst media 85 will work tobreakdown typical harmful gas pollutants.

In another embodiment, shown in FIG. 18D, said filter assembly 80consists of a photo catalyst media plus pre-filter 85, an activatedcarbon filter 84 and a HEPA particulate filter 82. Said pre-filter 85 isthe first filter element behind the filter cover 83 and protects saidactivated carbon 84 and HEPA filter 82. All filters are easily removableby users. An array of LEDs 86 is mounted on the backside of said filtercover 83. Said LEDs 86 can also be mounted around the wall of theenclosure close to the inlet. Said LEDs 86 and circuit is encapsulatedin a bio-compatible film or cover. Preferably, said LEDs 86 are turnedon only when ambient light intensity falls below a pre-definedthreshold, which is monitored by a light sensor. Hence, said photocatalyst media can always be activated if needed even when ambient lightis not available or insufficient.

In another embodiment, shown in FIG. 18E said filter assembly 80consists of a pre-filter 81, an activated carbon filter 84, a HEPAparticulate filter 82, and an outlet side photo catalyst media filter87. Said pre-filter 81 is the first filter element behind the filtercover 83 and protects said activated carbon 84 and HEPA filter 82. Allfilters are easily removable by users. An array of LEDs 88 is mounted onthe inside of the enclosure wall facing the outlet of said photocatalyst filter 87. Said LEDs 88 can also be mounted surround the wallof the enclosure close to the outlet. Preferably, said LEDs 88 areturned on only when ambient light intensity falls below a pre-definedthreshold, which is monitored by a light sensor. Hence, said photocatalyst media 87 is always activated even when ambient light is notavailable or sufficient. Said LEDs 88 and circuit is encapsulated in abio-compatible film or cover. In another embodiment, shown in FIG. 18Fsaid filter assembly 80 consists of a photo catalyst media pluspre-filter 85 and a HEPA particulate filter 82. Said pre-filter 85 isthe first filter element behind the filter cover 83 and protects saidHEPA filter 82. All filters are easily removable by users. Said photocatalyst media 85 is activated when daylight is available. Onceactivated, said photo catalyst media will work to breakdown typicalharmful gas pollutants.

In another embodiment, shown in FIG. 18G said filter assembly 80consists of a photo catalyst media plus pre-filter 85 and a HEPAparticulate filter 82. Said pre-filter 85 is the first filter elementbehind the filter cover 83 and protects said HEPA filter 82. All filtersare easily removable by users. An array of LEDs 86 is mounted on thebackside of said filter cover 83. Said LEDs 86 can also be mountedaround the wall of the enclosure close to the inlet. Said LEDs 86 andcircuit is encapsulated in a bio-compatible film or cover. Preferably,said LEDs 86 are turned on only when ambient light intensity falls belowa pre-defined threshold, which is monitored by a light sensor. Hence,said photo catalyst media 85 can always be activated if needed even whenambient light is not available or insufficient.

In another embodiment, shown in FIG. 18H said filter assembly consistsof a pre-filter 81, HEPA particulate filter 82 and a photo catalystfilter 87. Said pre-filter 81 is the first filter element behind thefilter cover 83 and protects said photo catalyst media filter 88 andHEPA filter 82. All filters are easily removable by users. An array ofLEDs 88 is mounted on the inside of the enclosure wall facing the outletof said photo catalyst filter 87. Said LEDs 88 can also be mountedsurround the wall of the enclosure close to the outlet. Preferably, saidLEDs are turned on only when ambient light intensity falls below apre-defined threshold, which is monitored by a light sensor. Hence, saidphoto catalyst media 87 is always activated even when ambient light isnot available or sufficient. Said LEDs 88 and circuit is encapsulated ina bio-compatible film or cover.

In another embodiment, shown in FIG. 18I, said filter assembly consistsof a pre-filter and an activated carbon filter. Said pre-filter is themain particulate filter selected to provide the required particularfiltering efficiency in addition to protect said carbon filter. Bothsaid pre-filter and carbon filter are preferably easily removable by auser.

The pre-filter and activated carbon filter can be stacked up as one userreplaceable assembly, such as by a simple heat gluing process. Theactivated carbon, said HEPA and photo catalyst filter can also bestacked up as one assembly. This HEPA filter preferably has 99.97%efficiency for particulates equal or above 0.3 um, which is equivalentto performance offered by most PAPRs. Said HEPA filter is preferablymade of fibreglass paper that is suitable for filtering solid and liquidparticles.

The activated carbon and photo catalyst filter work in a complementaryfashion—said activated carbon filter provides a general preliminaryfiltering for most harmful gases by blocking the harmful gases and slowthem down, it also works better in removing odours and VOCs, such asformaldehyde; while said photo catalyst filter continue to workspecifically to decompose the harmful gases to water and CO2, inparticular, CO, NO2, SO2, 03, and ammonia. It can also sterilize airwhich may contain germs, bacterial and virus.

The LEDs can be turned on/off by a user to control sterilisation of thefilter even when the device is not in use, such that germs and virus arenot built up. The LEDs can be turned on and off in sync with one'sbreathing. The LEDs can be any standard LEDs or UV LEDs. A light chambermatching the size and shape of said photo catalyst filter is used totransmit light from said LEDs. Preferably, a thin diffuser film is usedto transmit light evenly from said LEDs. Said diffuser film alsoisolates the LEDs from the air path. The activated and photo catalystfilter combination preferably have minimum 90% efficiency to CO. NO2,SO2 and 03 and work at this efficiency for at least 240 hours.

The photo catalyst media can also be applied as a coating inside saidmask and neck components. The coating can be a complementary measure tokill or inactivate most virus and bacteria when exposed to visiblelight. For all the filter configurations described above, an optionalcoarse filter can be added before the pre-filter to remove rather largeparticles often present in dustier environments, such as wood cuttingworkshops. Said coarse filter may be in low cost synthetic fibre andwashable or easily disposable, thus enabling longer use of the mainfilter. Said filters described above may be in any order or in differentcombinations.

Responsive Flow Control, etc

FIGS. 19A to 19E show various flow charts of the steps which may be usedin the responsive flow control of the flow generator module of thepresent invention, whereby the amount of air provided to the breathingchamber is breath responsive, and, the responsiveness is preferably alsouser adjustable.

FIGS. 20A-20B show a system diagram of examples of a responsive controlsystem in accordance with the present invention.

Most existing devices do not have flow control on a breath by breathbasis except those high end industrial/military types. Even when they dohave flow control, they are not responsive enough to breathing effortand the responsiveness is not user adjustable. Rather, a pressure sensoris often used to help maintain a positive pressure at the mask. More airwill be delivered to user's mask when the mask pressure goes towardszero, either by increasing the motor speed or by controlling an airflowregulator (USPC Class: 12820423). However, such a control mechanismtends to deliver insufficient flow to the wearer, especially duringdemanding breathing situations thus causing a sensation of discomfort.

None of the existing devices have the capability to allow directdetection of breathing effort on a breath by breath basis. Some otherrespiratory apparatus may have user configurable variable positive airpressure control, however, this is a fixed setting and not adaptive toone's real time breathing effort. As a result, the flow control is harshand not natural which limits the comfort one may receive.

None of the existing devices have the capability to allow user to adjustthe responsiveness of the flow control. However, in the real world,different people may have different demands for airflow. Even for thesame person, the demand for airflow may vary from time to time. Forexample, for a respiratory deficient patient, due to the weaker lungfunction, he or she may not have the same strength to breathe as anormal person. He or she may have the need to get more airflow with abreathing effort that is considered very weak by a normal person'sstandard. He or she may also wish to have the flexibility to control theairflow by his or her own breathing effort, even it is normally weakerthan a normal person, so that he or she can breathe in a more naturalway than that a harsh fixed control would allow.

The present invention uses either flow or pressure sensor to monitoruser's breathing effort. The rate of rise in airflow at the start of theinhalation is used as a signal to gauge user's breathing effort. Thehigher the value, the bigger the breathing effort. The MCU thencalculates the amount of flow required based on a user adjustable gaincontrol or breath responsiveness setting. The target motor speed is thenset at a value corresponding to the breathing effort at the start of theinhalation. Vice versa for the smaller values, where the target motorspeed will be set at a lower value accordingly. This feature will bebeneficial to respiratory impaired patient, as their lung muscles can beweaker than a normal person. The user can increase the gain to make theblower more sensitive to flow change, so he or she doesn't have tobreathe hard when more air in needed. This will relieve the breathingeffort for these patients and let the machine do the hard work. Hence,it improves comfort and provides health benefits to these patients.

The responsive flow control system, shown in FIGS. 20A-20B is one of thepreferred features of the system of the present invention, and it is ageneral term that relates to the main function of said flow generatorand its communication with said user interface control.

In one embodiment, the function of responsive flow control consists of ablower, a flow sensor with sensing air channels, a flow element, ablower outlet, a blower to mask air channel, an anti-aliasing low passfilter, a motor control power stage, a flow generator MCU2 based controlwhich consists of a A/D converter, Digital filter/conditioner, a RFCEngine, a VPAP Control Engine, a Motor Control Engine, a MCU2 COMMEngine. In addition, it also consists of a User Interface Control and aMCU1 COMM Engine.

The blower produces airflow according to said flow generator control.The motor speed determines the amount of flow to said mask.

The flow sensor detects flow according to pressure drop across said flowelement. In a preferred embodiment, said flow sensor is a mass flowsensor, based on thermo-anemometer flow sensing principle, and hasanalog output proportional to said pressure drop. In a preferredembodiment, said flow sensor has low input pressure range, typicallyaround 0.2″full scale, and said flow element is in fact a section ofsaid blower outlet with L around 5 to 40 mm. The blower outlet istypically in a round shape with a diameter D around 10 to 19 mm but itcan also be of any other shape with similar cross-section. The sensingair channels are preferably silicone tubes of suitable diameter. In apreferred embodiment, said anti-aliasing filter is formed by a simple RCnetwork with cut-off frequency between 100 Hz to 1 kHz. The signaloutput of said antialiasing filter is sampled by said A/D convener at 50kHz before being further processed by said digital filter/conditioner.Said digital filter has cut-off frequency around 30 Hz with 20 to 80 dBroll-off per decade. The output of said digital filter/Conditioner isfed to said RFC Engine at the frequency of said digital filter cut-offfrequency.

The operation of said RFC Engine is illustrated through FIGS. 22A-22B.Said RFC Engine works as a state machine, and its input contains thefiltered flow signal and the user setting on the breath responsiveness,and its output contains the target motor speed and breathing state. TheRFC Engines runs at frequency of that of the output of said Digitalfilter/conditioner and starts at IPAP Detection for inhalationdetection. Once detected, it samples said filtered flow signal at thefirst to third entry of said RFC Engine after the IPAP Detection evententry and the differences from said filtered flow signal at the IPAPDetection event entry is recorded. The recoded data is essentially therate of rise in flow and is used as a gauge for breathing effort. Thefinal breathing effort is derived after consideration of user breathresponsiveness setting or gain control on a breath by breath basis. Alook-up table containing motor target speed against breathing effort isthen used to output the required motor target speed to said VPAP ControlEngine to control the motor speed in a variable positive air pressurefashion. Said RFC Engine continues to monitor breathing state, and tocomplete the VPAP cycle according to sequences illustrated in FIGS.13A-13C before repeating it for every breath.

The motor control engine contains the motor driver firmware necessary todrive said motor. The motor control power stage contains power switches,their drivers and motor current sensing necessary to facilitate thedriving of said motor.

The user interface control receives user setting on breathresponsiveness or gain control before transferring it to the flowgenerator control. In a preferred embodiment, the transfer of usersetting is delivered via a single wire communication protocol betweenMCU1 COMM Engine and MCU2 COMM Engine.

The implementation of the responsive flow control can be achieved withother embodiment with the same spirit of the above embodiment.

In another embodiment, the flow sensor may have other suitable inputpressure range. The flow sensor can also be piezo-resistive type, andsaid flow element can be a laminar flow element. The sensing airchannels can be also part of the moulding structure for direct couplingto said sensor ports. The flow sensor can also have digital output. Saiduser setting can also be passed on to said flow generator control by anyother suitable means.

In yet another embodiment, a pressure sensor can also be fitted at thesimilar location of the flow sensor, where the pressure sensor candetect the air pressure at the flow generator outlet. In contrast withthe flow sensor embodiment, said pressure sensor detects the rate ofreduction in pressure at the start of the inhalation. The MCU thencalculates the amount of pressure required based on a user adjustablegain control or breath responsiveness setting. The target pressure isthen set at a value corresponding to the breathing effort at the startof the inhalation. The control for the target pressure is preferablydone via a proportional, integral and derivative (PID) control but itcan also be done by any other suitable schemes.

In a more advanced embodiment, the pressure sensor can be mounted insidethe mask, either in wired or wireless fashion.

The benefits of negative ions to humans are well known. However, none ofthe existing PAPRs employ a negative ion generator. A small negative iongenerator is mounted downstream of the blower, with two electrodes beingexposed in the air path so that the ions generated can be carried alongthe airflow to the user's airway.

The negative ion generator can be either a suitable standalone devicethat can be purchased off the shelf, or it can be customised completelyor partially to fit in the application.

The negative ion generator is preferably turned on only when motor runsto save energy and to increase life time. Its control can also be insync with breathing (on with inhalation and off with exhalation) tofurther save energy and to increase device life time.

Improved Manufacture and Mounting of a Toroidal Core for a Brushless DCMotor

Due to the particular requirements of the breathing apparatus, a newmanufacturing and mounting arrangement has been developed for a toroidalcore of a brushless DC motor, which is useful in the breathing apparatusof the present invention.

Examples exist in the prior art of brushless DC motors in which thestator is constructed by winding six coils around the periphery of atoroidal ferrite. This construction yields a compact motor which is verydesirable in some applications, for instance in a low-profile PAPR.

Significant problems with toroidal motors have however limited theirusefulness to date. These include, firstly, that it is extremelydifficult to keep the six coils separate.

When the second layer of windings on each coil is formed, it tends tofall off the side of the first layer and migrate into the area reservedfor the next coil. This difficulty has led to the coils generally beingwound by hand, which is not practical for volume production. A furtherproblem which occurs is that after the coils have been wound, theresulting stator is of an irregular shape (the coils not beingcompletely uniform) and it has no protruding features to form mountingpoints. However it is necessary to mount the stator very accuratelyconcentric with the rotor.

A solution which largely eliminates both problems with toroidal motorconstruction and so opens the way for the wider use of this type ofmotor, has therefore been developed, and will be described in relationto FIGS. 21A-21D. Coils are routinely machine-wound on toroidal coresfor other applications, for instance transformers. The difficulty inmachine-winding toroidal motor cores stems from the need to place sixsmall coils 91 around the periphery of the toroid 90 and prevent themoverlapping, as shown in FIG. 21A. Many machines are available forwinding transformer cores, for instance the RWE series from RUFF Gmbhand the STW-60 from Shining Sun Enterprise Co Ltd. Core winding issignificantly cheaper and more accurate with one of these machines thanby hand. However these machines can only be used where the outer face ofthe core is a plain cylinder without protruding ribs. This restrictionmakes it difficult to design a part or fixture to keep the six coilsrequired for a motor apart. A further difficulty is that any part thatis designed to be left in place when the coils are wound must be of amaterial that is not electrically conductive—generally polymers. Insmall motors this restriction makes a separate coil-separator componenttoo flexible to be of practical use.

The present invention overcomes these problems by placing radial fins 93on the core 94, forming a divide between each of the six coils 91 andits neighbour, as shown in FIGS. 21 A and 21B. It has been found byexperiment that the fins do not need to protrude onto the outercylindrical surface of the toroid, and for this reason the resultingcore is still suitable for winding using standard machines. The fins 93can be formed successfully in two ways. Firstly, they can be formeddirectly as shown in FIG. 21C, in the toroidal ferrite 94. For thismethod it is necessary to form the ferrite by injection moulding, ratherthan the usual sintering process. Secondly, they can be formed as shownin FIG. 21D by over-moulding a conventional toroidal ferrite core 94with a stiff polymer 95.

In practice it has been found that the second method is generally morepractical. However the ferrite material is brittle and the cores varysignificantly in size. For this reason it is necessary to encapsulatemost or all of the toroid in plastic, not attempting to blank-offagainst the toroid except where absolutely necessary to maintainconcentricity between core and over-mould. Such a design demands apolymer capable of flowing into very thin sections, but still very stiff(to resist the winding machine). Suitable polymers include polyamides(Nylons), liquid crystal polymer, Polybutylene Terephthalate (PBT) andvarious others. The amount by which the fins 93 protrude into theinterior of the toroid should be limited as much as possible to ensurethat a standard winding machine can be used. However it has been foundby experiment that fins the same height as the finished windings can bewound on standard winding machines at least down to a core innerdiameter of 20 mm.

The fins on the core are preferably designed to protrude slightly fromone or both sides of the completed windings. If this is done they can beused to mount the core in a reliable and repeatable way. If the statoris to be mounted in a motor housing made from an electrically conductivematerial such as a metal, care must be taken that the coils do not comein contact with it. Separation can be maintained if the fins areextended considerably beyond the coils on one or both sides of thestator and then used to mount the stator in the motor casing. However amore reliable and compact method of mounting is to place the woundstator in a thin plastic shell as shown in FIG. 21E. The shell is bondedto the stator using epoxy adhesive or similar material.

While the plastic shell takes up some space in the motor as shown inFIG. 21F, the size of the resulting stator assembly is extremelyrepeatable and it can be mounted tightly against even a metal motorcasing. For this reason the design with a plastic shell is more suitablefor high-volume production than the design that just relies on the finson the core to separate the windings from the motor casing. In ahigh-volume application the design with a plastic shell actuallyproduces a smaller motor than that without.

OTHER VARIATIONS AND MODIFICATIONS

It will be appreciated that a number of preferred embodiments have beenhereinbefore described. Numerous variations and modifications willbecome apparent to persons skilled in the art. For example, in FIGS.22A-22B is shown how a ‘visor’ may be optionally attached to the deviceto provide protection to the eyes of the user. As shown, the visor 29may be releasably attached to the attachment means 27.

All such variations and modifications which become apparent to personsskilled in the art should be considered to fall within the spirit andscope of this invention as hereinbefore described and as hereinafterclaimed.

What is claimed is:
 1. A breathing apparatus, including: a mask adaptedto substantially surround one or more of a mouth and nostrils of a user;a neck component adapted to substantially surround a rear portion of aneck of the user and including a flow generator to receive unfilteredair from a surrounding environment, filter the unfiltered air, andprovide filtered air to the mask; an inlet air channel arranged toconvey the filtered air from the flow generator to the mask; an airoutlet, separate from the inlet channel, arranged to convey air from themask; and a cooperating mating clip adapted to releasably engage theneck component with the mask and form a seal between the inlet airchannel and the mask.
 2. The breathing apparatus as claimed in claim 1,wherein the mask and the neck component include a portion defining partof the inlet air channel, and wherein the cooperating mating clipreleasably engages the portions forming a seal therebetween.
 3. Thebreathing apparatus as claimed in claim 1, wherein the inlet air channelis at least partly formed of an elastomeric material.
 4. The breathingapparatus as claimed in claim 1, wherein the cooperating mating clipincludes an adjustment mechanism for moving and retaining the maskrelative to the neck component.
 5. The breathing apparatus as claimed inclaim 4, wherein the adjustment mechanism includes a ratchet mechanismand a release mechanism, and wherein the ratchet mechanism is decoupledupon activation of the release mechanism, thereby allowing the mask tomove relative to the neck component.
 6. The breathing apparatus asclaimed in claim 1, further including componentry for operation of thebreathing apparatus, wherein the componentry for operation of thebreathing apparatus is arranged within the neck component.
 7. Thebreathing apparatus as claimed in claim 1, further including at leastone of a cover, to decorate said mask, and a visor, to protect a face ofthe user.
 8. The breathing apparatus as claimed in claim 1, furtherincluding a strap adapted to be attached over a head of the user, toretain the mask in position.
 9. The breathing apparatus as claimed inclaim 1, further including at least one of a flow sensor and a pressuresensor, the flow sensor and pressure sensor configured to provide afeedback signal to the flow generator to adjust at least one of air flowand air pressure of the mask.
 10. The breathing apparatus as claimed inclaim 1, wherein the neck component further includes at least one paddedportion arranged to abut the neck of the user.
 11. The breathingapparatus as claimed in claim 1, further including an exhaled air filterarranged to filter air emitted from the air outlet.
 12. The breathingapparatus as claimed in claim 11, wherein the exhaled air filter isintegrally formed with an exhaust port.
 13. The breathing apparatus asclaimed in claim 11, wherein the air outlet extends between the mask andthe neck component and includes an exhaust port arranged proximal to theneck component.
 14. The breathing apparatus as claimed in claim 1,wherein the inlet air channel and the air outlet open to the mask atopposite sides of the mask, so that the airflow is arranged to flowacross the mouth or nostrils of the user.